Room ionization systems typically feature a number of tungsten points or similar emitters which generate positively charged ions, negatively charged ions, or both. The ions produced by these emitters migrate to the work area and neutralize charges on objects in the work area.
The emitters generate ions when excited by high voltage energy. A centrally located control unit and power supply typically distributes high voltage electricity to the emitters through a network of high voltage conductors. The emitters are typically located overhead in or near the ceiling of the area, and a curtain of moving air provided by blowers helps transport the ions to the work area.
One typical area ionization system provides alternating current to the emitters. The emitters in such "AC" systems thus produce alternating waves of positive and negative ions. Another typical type of area ionization system provides successive pulses of DC voltage to the emitters. For instance, the emitters receive a first pulse of positive DC voltage followed by a pause when no voltage is supplied, followed by a pulse of negative DC voltage. The pulses may be of varying length and strength, and the pauses may be of varying length or omitted. Such "pulse DC" systems can thus approximate AC systems when the pulses are shaped and timed appropriately. The pulse DC systems accordingly also generate ion waves.
The AC and pulse DC ionization systems follow the conventional wisdom that positive and negative ions generated close to one another at the same time will attract each other and cancel themselves. Those systems thus seek to produce a sufficient number of ions of a first polarity and allow them to migrate sufficiently far from the emitters before switching polarity of the emitters to generate ions of the other polarity. Although a certain percentage of ions in successive oppositely polarized waves cancel each other, a supply of positive and negative ions does reach the workspace.
The ion waves produced by AC and pulse DC systems exhibit normal wave behavior, however. First, such waves of ions superimpose themselves on one another. Ion waves produced by a first emitter cooperate with ion waves produced by other emitters to add together not unlike waves which combine at the seashore. This superposition causes the work area to receive alternating concentrations of positive ions and then negative ions over time, rather than a simultaneous balanced supply of both ion types.